Carburetor of the fuel injection type



March 18, 1958 A. LENNING 2,827,271

CARBURETOR oF THE FUEL INJECTION TYPE Filed oct. 22, 1954 I 2 sheets-sheet 1 Fig. Ja' ffy. 5b

TTFPNEVS March 18, 1958 A. LENNING l 2,327,271

CARBURETOR 0E THE FUEL INJECTION TYPE Filed oct. 22, 1954 2 Sheets-sheet 2 INV EN TOR.

4Q VM Z E/v/v/A/G 2,823,271 Patented Mar. 18, 1958 fico CAFIURETCR F THE FUEL INJECTIGN TYPE Adver leuning, Stockholm, Sweden, assignor to Aktiehoia et Kaba Stockhoim Sweden app-dentiera Plhctol'ner 22, 1954, Serial No. 464,145

Ciaims pr'ority, application Sweden March 29, 1954 4 Ciaims. (Ci. 261-37) My invention has for its object an injection type carburetor primarily to be used with 2-cyc1e single cylinder combustion engines employing volatile fuel. The new carburetor may be looked upon as a further development of the carburetor described in U. S. Patent No. 2,694,386 issued November l5, 1954.

The general aid of the invention is essentially the same as in the previous patent, i. e. the new device is to serve the purpose of improving the performance of small sized ffl-cycle combustion engines` in such engines the quantity of fuel to be dissipated into the intake air at each power stroke is comparatively small, at full load being of the magnitude of cubic millimeters when the cylinder volume amounts to 5 0 cubic centimeters. When idling the engine will require less than half of said quantity. The problem of obtaining dependable operation at such small injection volumes involves a rather high degree of precision in producing the pump sleeve, the pump piston and in the attendant valve functions. Such precision work tends to make the manufacturing costs high. In choosing a proper design, and the proper material for same, one also has to consider the influence of wear. These considera tions lead to the conclusion that the pump should have only a minimum number of moving parts and that the piston diameter should be small in relation to the pump stroke. Furthermore the volume of liquid to be injected into the air intake at each stroke should be manually variable to suit different fuels, changes in air and engine temperatures and to compensate for mechanical wear in the pump.

Additionallylthe device should produce an effective pump stroke which automatically follows the position of the air intake throttle in accordance with a curve to be determined experimentally once and for all. It should also incorporate a tightly closing automatic valve to prevent fuel from a pressure fuel tank from leaking into the engine, or from going to waste when the engine is at a standstill. Around these requirements the new injection device has been designed.

The invention is described hereinafter in conjunction with the accompanying drawings in which,

Fig. l is a cross sectional view taken horizontally through the carburetor, here shown in its normal position on the engine crank case;

Fig. 2 is a corresponding vertical cross section;

Fig. 3 is a cross section taken at x-x in Fig. 2;

Fig. 4 is an exterior end view;

Figs. 5o and 5b are developments of cylindrical throttle members incorporated in the device, and the same reference numbers are used throughout; and

Fig. 6 is a vertical cross sectional view similar to Fig. 2 but showing the pump sleeve in section.

ln Fig. l numeral 1 represents a perforated air lter cap which is mounted on one side of a pump body 2. The pump body is transversed by two a step cylindrical bore to accommodate an axially slidable pump sleeve 3, having a central piston 4. The pump sleeve is provided with a supply tube 13 for the fuel (an oil-gasoline mixture) and is to be assembled into the pump body from the right, the tube 1S fitting into a slot 5 (Fig. 2) in the pump body. The right end of the pump sleeve 3 is kept in alignment with the bore by means of a stationary sleeve 6 surrounding a movable throttle sleeve 7, these two sleeves constituting a pair of throttling members. Throttling action is effected by turning sleeve 7 through a desired angle, causing the apertures in sleeves o and 7 (see Figs. 5a and 5b) to co-operate in cutting of, or admitting, intake air, the path of which is indicated by the air stream lines in Fig. 1.

The pump sleeve 3 is continuously pressed towards the right by means of a helical spring 9, the spring pressure being transmitted by the fuel tube 13 and the throttle member 7 to a setting member l@ which is screwed into the pump body from the right. This setting member has a central aperture to accommodate a shaft extension S from the throttling member 7.

The pump sleeve 3 has no inlet non-return or check valve since the piston 4 (see Fig. 6), on its pump stroke, cuts off the inlet aperture after a short distance of travel. There is, on the other hand, an outlet check valve, here shown as a cylindrical, resilient rubber sleeve 11 which normally closes off a radially disposed outlet aperture 2t) (Fig. 6) for the fuel. This rubber sleeve may, for the purpose of priming, be stretched away from said aperture by means of a wire member 12 (more clearly shown in Fig. 3) which engages with the throttle sleeve 7 when the latter is turned through an angle beyond its normal idling position.

The extension shaft 8, which is for governing the engine, is equipped with a handle 19. This handle carries a friction member 13 which by means of a wire spring 14 is kept pressed against the circumference of an adjacent cylindrical portion of the pump housing, and is intended for producing enough friction to prevent accidental change of the setting of handle 19. This wire spring also serves the purpose of cooperating with the stop pin 15 for the full load position of the handle 19, and with the stop pin lo fo-r the idling position. The idling stop is, however, not a fixed one since the arrangement of the spring 14 is such as to permit a continuation of the handle movement beyond the idling point, against the spring force, this movement being for priming as already described.

The apparatus operates in the following manner. At the full load position, corresponding to Figs. l, 2, 3, and 4 the intake air will intermittently be drawn into the cylinder (not shown) along the air stream lines in Fig. 1. synchronously, and preferably in phase, with the air pulses, fuel will be injected into the intake air as this is moving past the spray nozzle formed by the rubber sleeve 13 in conjunction with the fuel aperture covered by said sleeve. The pump piston 4 is to be actuated by a cam or the like (not shown) on, or mechanically connected with, the engine shaft.

The quantity of fuel which is injected into the intake air at each pump stroke is determined by that part of the piston stroke which takes place beyond (i. e. to the right of) the inlet opening from the tube i8. Said part, or phase, of the pump stroke may be termed the effective pump stroke. it should be obvious that the effective pump stroke increases as the pump sleeve is moved towards the left, say by screwing the setting member l@ inwardly, provided the total pump stroke so permits.

ln case no other means of regulation were to be provided the effective pump stroke would be constant for each setting of the member lo, and would thus be independent of the air throttling. This is undesirable since the air-gas mixture would then be too rich, when the engine is set to idle, i. e. when the density of the intake air issubstantiallyy reduced;Y To compensate for the reduction-fand to-produce ythe proper Vmixture at all*-v Usuall SaLworn'.' um' `vreouiresfa reductionin'the decrease of the pump stroke at the'idlingposition;oWin-gtothe largerfuellleakage p'astthefpiston atten'dantto a' worn pump; Itshouldz'thus:Betapparentthaethenew carburetor: comprises: tw'o indep'endent means for" governing' the.

stroke-:isi toi be-Iset; theotherlme'ans bein'g-thei governing f curve C by which the correct'reductionl of'thelpumplstroke; as :re'quiredifo'r partjloa'ds, orf'idling; isleiected'j Within 1 the r scope f of the? inventionall idea the i injection devicenovv havinglbeenldscribed maylbe'varied inseveral ways; Y withan eccentricrrather! thanxvith a. cairrlcurveias Sslowh'" Y in Fig:V 5b; .to:serve theSsame-fpnrposei In Ytlztatcase theV axis of. the f. throttling 1 member: should. preferably bei at right 'angleswiththat fofzthe'rpumpsleeve.'v

I claim:

1. An:injectionltypefcarburetorfparticularly'forfZcycle' combustionlengines; comprising, ini' combination; alpumps The throttling.vv sleeve r7." may-"e1 gt. be; providedhousing, a pump sleeve mounted in saidihousing; a

pistonhavinga constant stroke; means mounting said pistonlinv saidi pump sleeve; a1 manuallyv operable? air' throttle valve, and means 'onsaid'air throttlevalvefor adjusting the positionlofsaidi pumpisleevexto vary the effectiveI strokeioffsaidpump pistonv 2. .An inj'ection typefcarburetorparticularly for 2-'cy'cle`f'v combustion engines; comprising, in '-combinatiomal pump'v housing, a cylindrical. ,bore'r in said housing,v a pt'un'pl` sleevef. mounted. ini' Vsaid-*bore andaxia1ly adjustable, al

piston mounted'l'i v:said pumpfsleevegrsaid piston =havingl a constant'stroke, the eiective portion Vof saidstrokei being adjustable by'axial adjustment of said 'pump' sleeve,"y

a manually'rotatable cyli'ndri'cal -iai-rfsupplyl sleeve; andi-a4V Y cam onfzone edge2of?saidzsleeve:cooperating withf/said pump sleeve for adjusting the position of saidpumpfslee've in 'responseto Echanges in `th'e tlrottl'efse'tting.'V

3;; An injection 'typecarburetorlpartieularly forfZ-'cycrlef conibustionfengines, comprising, lincombination, afpump housingihavingsa'CylindrCalbOre therein', an air throttle' sleeve-mounted inhsai'd bore, aL-cooperatingiair throttle sleeve mounted Within said first sleeve, said air throttling sleeves.having-apertures.therein, said-inner sleeve being rotatable with respect to said outer sleeve to throttle the air supply, a pump sleeve mounted within said inner air throttling sleeve and axially displaceable with respect thereto, ay piston mounted in a bore in said pump sleeve, a fuel passage communicating with saidV bore, manually operablemeansfor adjustingthe positionYAY of said pump sleeve axially Yof" said pump housing and `relative to said pump.' pistbn'WherebyfSaidpStOns eective stroke may` be adjusted whileitsftotalstrokelrem'ains constant, and means onsaid inner air-throttling.. sleeve for adjusting the axial"position otsaidlpiirnpV sleeve to4 decrease the eectiv'e strokewheni saidVl inner' throttlingmetnber is rotated to a position corresponding to idling of the engine.

4. An injection 'type carburetor particularly for 2-cycle Y combustion engines, comprising, in combination, a pump housing comprising a generally cylindrical bore, a stationary= air throttling sleeve* mouitlted'i in saidV bore,V a rotatable:airfthrottling sleevecooperatingwith said sta= tionary'fsleeve'to'regulatetthe air' supply to the'engine,

said sleeves; h'avingf substantially danletricallyv spaced Y aperture'stherethrough, the position of said aperturesV being adjustable Withrespect to `one another, means car-` ried on'rsaidinnerairthrottling sleeveefor rotating said sleeve with' respect to' said` stationary sleeve, a` pump sleevef mounted -in` said1inner throttlingV sleeve, ay fuel supply pipe 'mounted' atisubstantially right angles Tto said pump'v'sleeve-andi extending through an opening in said pump' housinggvan Vaxialbo-re-in'said' pump sleeve, said Y bore'communicatingl'with' said' fuel supply pipe, springV means pressingl'said'pump sleeveandfuel supply pipe in one direction, said' pipe" bearing against said-nner throttli'ng valve, manually-'operable means'for pressing said innerl thro-ttlingfsleeve, fuelsupply pipe and pump sleeve'in the' oppositedirection, a piston'mounted in said bore in said pump'sleeve; an outlet from said bore extend-'- ing radially'of'said pump sleeve and 'communicating with:

the air passagef Within saidiinncr throttling-cylinder, and means carried 'by-'saidinner'throttling cylinder and operable'upon rotation'th'ereof to idling position to permit saidspri'ng'to move said pump sleeve to a position to decrease *its effective stroke to thereby adjust-fthe fuel supply relativeitoltheair supply to permitproper idlingy of thelengine-L Y Y Rfrences Citedin Vthe le of this patent UNITED STATES PATENTS LINTEE STATES PTEENT FFICE CERTEHCZE Patent Noa 2,8275271 March 18, 1958 Alvar Lermng It is hereby eertfe that error appears in the above numbefed patent requ'fng Correction and that the :said Letters Patent should read as Corrected below.,

In the grant, line l, and. in the heading to the printed specification, line 3, name of inventor, for "Alvar Leaning read u Alvar Lelmng we Signed and sealed this 6th day of May 1958.,

(SEAL) Atest:

KARL H mlm ROBERT co WATSON Ati/@Sting Ofer Comissioner of Patents 

